File mime type checker
| Name | |
| Size | |
| Type | |
| Last modified date |
What this file MIME type checker does
Upload or select a local file and the tool reports its detected media type, size, name, and last-modified metadata where the browser exposes them. The MIME label summarizes what the bytes look like to a lightweight inspector—useful when an attachment arrives as report.pdf.exe or when a PNG was saved with a .jpg extension. This is not a full antivirus verdict; it helps you catch innocent mistakes and obvious mismatches before they reach server-side pipelines.
When to use it
Use it while debugging upload forms, validating user-supplied assets before you pipe them into imagemagick, or triaging a suspicious download without opening it in its native app first. After you know the true type, route heavy image work through Image optimizer or format converters, and keep comparing extensions to MIME labels in your backend validators—not trusting either alone.
Worked example
Support forwards invoice.zip that behaves oddly. The checker reports a MIME of application/x-php or plain text instead of a zip signature. You block it at the WAF and ask the sender to resend from a known channel—without executing the payload. If the MIME matches image/png but marketing insists it is a SVG workflow, you investigate whether someone renamed layers manually.
Frequently asked questions
Why does MIME differ from the file extension?
Extensions are user-editable labels; magic-byte sniffing looks at the opening bytes. Trust content for security decisions, not the suffix alone.
Can embedded polyglots fool this?
Cleverly crafted files can confuse simple sniffers. Combine scanning, sandboxing, and least-privilege execution for anything untrusted.
Does it upload my file to your servers?
Assume browser-local handling for typical SPA-style tools, but check your network tab if your deployment wraps uploads—policy belongs in your privacy statement.
Why is last modified missing?
Some drag-and-drop sources strip timestamps or return synthetic values; treat metadata as hints.